1. Field of the Invention
The present invention relates to a vehicle control device, a vehicle control method, and a computer-readable medium having, encoded thereon, a program for providing appropriate vehicle control responsive to detection of an object ahead.
2. Description of the Related Art
Vehicle control devices have been proposed in the past for obtaining various information regarding vehicle travel such as a current position identified by GPS or the like and road information obtained from map data in a navigation device, as well as for providing driver notification and driving assistance, and for intervening to automatically control driving to prevent a vehicle accident. This type of vehicle control device executes vehicle controls at diverse timings and based on various conditions. In particular, when an object such as another vehicle ahead is detected during vehicle travel, in order to avoid contact with the object or mitigate damage upon contact, the vehicle control device performs braking to decelerate and turns the vehicle.
Japanese Patent Application Publication No. JP-A-2007-145152 (pages 6 to 7, FIGS. 4 to 6), for example, describes a braking control system, wherein based on the speed of host vehicle, the speed of an object ahead of the host vehicle, and a positional relationship between the host vehicle and the object, it is determined whether contact with the object can be avoided by steering the host vehicle. If it is determined that contact with the object cannot be avoided by steering, then the braking control decelerates the vehicle.
In cases where the host vehicle is approaching an object ahead, contact with that object can be avoided by:
(1) Maintaining a safe distance from the object by braking the host vehicle while keeping the current direction of vehicle travel.
(2) Performing an avoidance maneuver by steering to change the travel direction of the host vehicle so that the vehicle goes to the right or left of the object.
However, in order to avoid contact with the object by braking (method 1), the driver must conduct a braking operation which requires more time than that required to avoid contact with the object by steering (method 2).
In the vehicle control system described in Japanese Patent Application Publication No. JP-A-2007-145152, if it is determined that contact with an object is unavoidable merely by steering (method 2), namely, if contact with an object cannot be avoided regardless of any vehicle steering operation, then braking control must be initiated. The determination of whether contact with the object is avoidable by steering is based on the relative speed and the positional relationship between the host vehicle and the object as described above, that is, based only on relative relationships between the host vehicle and the object.
However, the vehicle cannot avoid an object ahead by moving into the right or left adjacent lane if conditions do not allow such an avoidance maneuver, such as when there is no adjacent lane next to the lane in which the vehicle is traveling and when, if there is an adjacent lane next to the lane in which the vehicle is traveling, there is another object (e.g. a traveling vehicle) in the adjacent lane. If a determination is made based solely on a relative relationship between the host vehicle and the object as in the related art, then it is impossible to determine that the vehicle is in a situation where contact with the object cannot be avoided by steering.